Voronoi residuals and other residual analyses applied to CSEP earthquake forecasts

Voronoi residuals, deviances, super-thinning, and some other residual analysis methods are applied to a selection of earthquake forecast models in the Collaboratory for the Study of Earthquake Predictability (CSEP). Unlike simple numerical summaries such as the N-test, L-test, or R-test, graphical residual methods are proposed which can be useful for comparing multiple models and for highlighting when and where a given model does not agree closely with the observed seismicity. For gridded forecasts, deviances seem ideally suited for model comparison, and Voronoi residuals seem preferable to simple grid-based residuals for assessing one model individually. For models outputting an estimated conditional rate at any particular space–time location, Voronoi residuals and super-thinning can be especially useful at identifying departures from the data.